KR100346067B1 - Steel tire cord improved in corrosion-resistance and its production method - Google Patents

Abstract

The present invention relates to a steel tire cord having improved corrosion resistance and a method of manufacturing the same.

Steel tire cord of the present invention is coated with a 0.01-0.5% by weight solution of 8-azadene (azaadenine) on the surface of the steel tire cord or the plated layer of the filament constituting the steel tire cord and dried 8-azadenine (hereinafter referred to as' azadenine There is a technical characteristic in forming the coating layer.

In the manufacturing method of the present invention, a wire, such as a filament or a steel tire cord, is pre-wound when a steel plate is manufactured by drawing a brass plated steel wire and filaments constituting a steel tire cord for reinforcing tires or a plurality of filaments. The 8-Azadenine solution was deposited on the surface of the brass plating layer of the wire by depositing in the denin solution, and the 8-Azadenine solution coating layer was dried with hot air of 200 ° C. or higher to form an 8-Azadenine coating layer, and then wound up. It consists of a series of processes, in the case of a steel tire cord may be applied a method of applying the 8- azadenine solution in addition to the above-described drip equation.

The azadenine coating layer formed on each filament constituting the steel tire cord of the present invention or on the outer circumferential surface of the steel tire cord as a whole may improve the corrosion resistance of the steel cord even by using a low concentration solution, which may be effective in extending the life of the tire. In addition, especially in the case of exports that are stored for a long time or are transported for a long time due to exposure to the air, the 8-Azadenine solution can be effectively coated to increase the concentration of the 8-Azadenine to effectively suppress the surface degradation of steel cord products. There is this.

Description

Steel tire cord improved in corrosion-resistance and its production method}

The present invention relates to a steel tire cord (hereinafter referred to as 'steel cord') having improved corrosion resistance, and more specifically, to form a coating layer of organic material reacting with copper on a brass plating layer formed on the outer circumferential surface of the steel cord. The present invention relates to a steel cord having improved corrosion resistance without reducing the aging adhesive strength of the steel cord to rubber by inhibiting the reaction with oxygen, moisture, or the like.

Steel cord is a kind of wire for rubber reinforcement, and is coated with brass (copper 60 ~ 70 wt%, zinc 30 ~ 40 wt%) on high carbon steel, which usually has carbon content of 0.6 ~ 0.85wt%, and then cold drawn It is made of brass plated filament of the required diameter by processing, and it is twisted into various structures by combining it into several strands and used for reinforcement of tire rubber. The filament means one fresh wire.

The brass plating layer coated on the steel cord is to enhance adhesion to rubber, and the copper component of the brass plating layer combines with the sulfur present in the tire rubber to form a copper-sulfur compound to increase the adhesion between the steel cord and the rubber. Play a role.

However, it is necessary to oxidize the surface of the steel cord by exposure to air inevitably from the drawing of the brass plating wire to the molding of the tire rubber, that is, the production, shipping and use of the steel cord product, and the tire use time after the tire molding. Due to the growth and deterioration of the copper-sulfur compound layer under the influence of moisture, heat and oxygen, the adhesion between the steel cord and the rubber inevitably falls.

Therefore, the problem of improving the initial oxidation of the steel cord by the exposure to the atmosphere and the adhesion over time, that is, aging adhesion is an important problem that is directly connected to human life, and many studies have been conducted.

In order to improve the aging adhesive strength of brass plated steel cord, a method of changing a binary alloy plating layer of copper and zinc into a ternary alloy layer by adding one third element such as cobalt, nickel, molybdenum, and chromium is described in US Patent 4,226,918 And 4,255,496.

The ternary alloy plating method of the US patent is a method of improving the aging adhesion by adding one of the third element, such as cobalt, nickel, molybdenum, chromium, to the brass plating layer on the surface of the steel cord made of copper and zinc, The addition of the third element, which is stable against corrosion, has the advantage of suppressing the corrosion of the final steel cord, but the drawability is poor in the drawing process and the adhesion is low because there is no adhesive functional group bonded to the rubber for the tire in the plating layer. I have a problem.

The oil coating method is disclosed in Korean Patent Nos. 2402 and 136571 as another method for improving the aging adhesive strength. However, the degree and uniformity of the amount of oil applied may affect the adhesion to rubber and Therefore, there is a problem that the degree of corrosion of the steel cord is different.

In addition, since the oil not only contains oxidation-causing substances such as sulfur but also degrades the initial adhesion with rubber, the oil reduces the friction force between the steel cord-guide rollers in the twisted pair process, thereby improving the twisted pair workability. The present invention is applied for the purpose of minimizing surface defects.

In addition, there are new methods different from the above methods, US Patent No. 3,926,703 discloses a method of forming a halogenated sulfonamide coating layer used as an adhesive for tire compounds on the surface of the steel cord, and 4,182,639 It is known to apply sulfur and phosphate corrosion inhibitors to steel cord surfaces.

In addition, U.S. Patent Nos. 4,269,877 and 4,441,946 have a method of coating with benzotriazole amine to improve aging adhesion in a humid atmosphere and a method of improving water aging by forming a phenol formaldehyde-based resin film. The present invention discloses a method of coating a metal surface with a chemical having both an amine group and a nitro group at the same time.

However, the patents are for the purpose of improving the aging adhesive strength of the steel cord, and not a technique for improving the corrosiveness.

In the present invention, by coating the organic material on the surface of the wire after the wire processing of the conventional copper or copper alloy plated iron wire to suppress oxidation of the surface of the wire by exposure to the air, the initial adhesion to the tire compound is somewhat reduced. Finally, after the tire is formed, the corrosion resistance of the steel cord itself due to the use of tires, ie, heat, salt water, and moisture, can be slowed down, thereby reducing the durability of the steel cord due to the decrease in adhesion and tensile strength due to corrosion of the steel cord. To provide a corrosive steel cord and a method of manufacturing the same.

1 is a schematic diagram of a fresh line with an 8-azadenin deposition tank and a dryer installed;

2 is a schematic diagram of a twisted pair line in which an 8-azadenin deposition tank and a dryer are installed.

Figure 3 shows the chemical structure of 8-azadenin,

(A) is a chemical structural formula,

(B) is the bonding structure of 8-azadenin and copper.

4 is a perspective view of a steel cord specimen for examining corrosion potential velocity.

((Explanation of symbols for main part of drawing))

1. Fresh line 2. Stranded line

11,21. Withdrawal Capstan 12,22. Azadenine Sedimentation Tank

13,23. Dryer 14. Fresh Dice

The above object of the present invention is achieved by applying and drying 0.01 to 0.5% by weight of azadenine solution on the surface of a steel cord or a plated layer of a filament constituting the steel cord and forming a method.

The 8-azadenine solution is prepared by heating and dissolving in a solvent such as water, methanol or acetone, and the azadenine coating layer is a drawing process for cold drawing steel wire into filaments or a twisted wire process for associating filaments to form various twisted structures. In, there is a technical feature to drip the fresh filament or stranded steel cord in the azadenine solution or to drop the azadenine solution on the surface and to dry it.

The azadenine coating layer forms a copper component and a chemical bond to prevent the copper component present on the surface of the brass plated layer of the filament or the steel cord from adhering to oxygen, thereby forming a sulfur plating in the compound rubber for the tire and a brass plated layer of the steel cord. The initial reaction rate during the mutual reaction of the contained copper is lowered to reduce the initial adhesion of the steel cord to the compound rubber for the tire, but to suppress the growth of the copper sulfide layer due to the heat generated during tire molding, It suppresses the corrosion of the steel cord by heat and moisture, thereby reducing the rate of aging adhesion decrease.

That is, the corrosion resistance of the steel cord is improved by maintaining the copper component of the brass plating layer of the steel cord outer circumferential surface in a more stable state against heat or moisture.

Details of the technical configuration, specific characteristics, and the like of the steel cord having improved corrosion resistance and a method of manufacturing the same will be clearly understood by the following description with reference to the accompanying drawings.

1 is a schematic diagram of a fresh line to which an azadenine deposition tank and a dryer are applied, and FIG. 2 is a schematic view of a stranded line to which an azadenine deposition tank and a dryer are applied.

As shown, the azadenine deposition tanks 11 and 21 and the dryers 12 and 22 are filaments which have passed through the fresh die 14 and the twisted pair 24 of the fresh line 1 and the stranded line 2. 15 and steel cord 25 are provided immediately before the extraction capstans 11 and 21 so that an azadenine coating layer is formed before passing through the extraction capstans 11 and 21. The method of applying the azadenine solution to the steel cord may be a dropping method instead of the above deposition method.

Since the advancing speed of the filament and the steel cord is very fast in the drawing line or the stranded line in which the azadenine solution is applied, the azadenine coating layer should also be dried quickly, and should be dried at a high temperature of 200 ° C. or higher with hot air.

As described above, the azadenine chemical structure of the azadenine coating layer formed on the surface of the brass plated layer of the filament or the steel cord and the bonding structure of copper are illustrated in FIGS. 3A and 3B.

As shown, by replacing the hydrogen bonded to the azadenine copper of the brass plating layer, the azadenine is combined with the brass plating layer to stabilize the surface of the plating layer against the external environment.

As an embodiment of the present invention, the azadenine solution by concentration of 0.01 to 3% by weight on the surface of the steel cord stranded in a 3 × 0.22 mm + 9 × 0.22 mm + 0.15 mm structure using a fresh brass plated filament Was added dropwise and dried to form an azadenine coating layer.

Comparative tests were performed on the corrosion rate, initial adhesion, thermal aging, salt age and moisture aging adhesion between the steel cord and the untreated steel cord on which the azadenine coating layer was formed. Potentiometer 273A, a potentiometer of EGG), was used, and a 5 wt% sodium chloride solution was used as the electrolytic solution.

At this time, the steel cord specimen deposited in the sodium chloride solution, as shown in Figure 4, the length of the specimen (4) to 15cm, and forms an enamel coating layer 41 at one end of the specimen, that is, the cut portion where the iron base material is exposed to the outside The steel cord is left as far as 3 cm (43) from the boundary between the steel cord 44 and the cut portion coating layer, and the enamel coating layer 42 is again formed in a suitable length from the steel cord after 3 cm.

Then, after encapsulating the enamel uncoated portion 44 having a length of 3 cm in contact with the cut portion of the steel cord specimen 4 in an electrolytic solution, a DC power was applied to the steel cord to investigate the potential change, and the corrosion rate was changed to the corrosion potential change. It was set as a relative comparison with time.

In this test, the faster the corrosion rate, the lower the corrosion potential value with time, and the slower the corrosion rate, the slower the change value. This means that the exposure of the iron base material occurs due to the corrosion of the brass layer on the surface of the steel cord. Since the exposure of the base material increases as the corrosion progresses, the initial corrosion potential is due to the corrosion at the corrosion potential values of brass and iron. This is because the loss of the brass layer ultimately results in corrosion of the base metal.

Compound composition for the tire used in the present embodiment is shown in Table 1 below.

Product Name Usage (PHR) Natural ointment 100 Carbon black 50 Silica 10 Oxidized zinc 5 sulfur 3 Cobalt compound 3 Phenolic Resin 2 Fragrance Ball Refinery 2 Melamine 2 Amine Anti Aging Agent One

The vulcanization condition of the compound for the tire and the steel cord is 150 ° C. × 30 minutes × 34 atm, and the heat, saline, and water aging adhesion test conditions of the vulcanized inventive examples and comparative example steel cords are shown in Table 2 below.

Test Items Aging Conditions Heat aging 100 ℃ × 3 weeks Salt aging Room temperature 20 Joules% Brine × 3 weeks Water aging 70 ℃ X Relative Humidity 95% × 3 weeks

Examples and Comparative Examples According to the above conditions Corrosion rate and initial, thermal aging, salt aging and moisture aging adhesion of steel cords by azadenine concentration are shown in Table 3 below.

division Azadenine solution concentration (% by weight) Corrosion rate Adhesion Early Heat aging Brine aging Water aging Comparative example No treatment One 100 50 80 75 Example 1 0.01 0.9 90 52 81 74 Example 2 0.02 0.9 87 54 83 76 Example 3 0.03 0.7 85 55 85 80 Example 4 0.05 0.7 80 50 81 80 Example 5 0.1 0.5 75 45 73 70 Example 6 0.5 0.4 55 43 70 68 Example 7 One 0.3 25 20 25 24 Example 8 3 0.3 24 18 24 23

* Adhesion test was conducted according to ASTM D-2229.

* The adhesive strength is set to 100 the initial adhesive strength of the comparative material before treatment

Relative comparison value.

* Corrosion rate is ² cm ² in 5 wt% saline solution.

By exposing the steel cord area, the corrosion potential value reaches -0.58 V.

Relative comparison of time (seconds) as reference value 1.

Comparing the corrosion rate of the steel cord of the comparative example steel cord without azadenine coating and the steel cord of the azadenine coated example steel cord, the corrosion rate tended to decrease as the concentration of the azadenine solution increased. In addition, since the initial adhesive force is lowered, it is preferable to select the concentration of azadenine so that the rate of decrease of the initial adhesive force is 20% or less.

In the adhesive strength between the tire compound and the steel cord, the initial adhesive force obtained after vulcanization is called initial adhesive force, which is a measure of the initial vulcanization state between the steel cord and the rubber for the tire, and the initial adhesive force must be a certain level or more. Since the initial adhesive strength of the steel cord varies depending on the structure of each steel cord and the tire compound used, there is a criterion for the initial adhesive force of each tire manufacturer, and the steel cord structure and the tire used in the test of the present invention example and the comparative example. The solvent compound should be at least 80, the concentration of the azadenine solution to satisfy this is less than 0.05%.

The aging adhesive strength is due to the deterioration of the adhesive state between the steel cord and the tire rubber due to fatigue and deformation heat and moisture applied to the tire rubber and the steel cord due to friction and load with the ground as the tire use time increases. As a test, the test is carried out by leaving the steel compound vulcanized together with the steel cord in the atmosphere where the temperature, humidity, and reaction conditions are maintained for a certain time, and then inspecting the adhesion between the steel cord and the tire compound. It is made by the method of comparing with adhesive force.

Since the adhesive force after the predetermined time is inevitably lower than the initial adhesive force, the smaller the adhesive force decreases, the more stable aging adhesive properties, so the most preferable condition of the steel cord is that the adhesive strength as close to the initial adhesive strength as possible to all ages It is desirable to maintain.

Accordingly, it can be seen from Table 3 that the azadenine solution concentration range of the Examples obtained the equivalent or more results of the aging adhesive strength than the comparative material without azadenine coating is 0.01 ~ 0.05% level, the most preferred concentration range is 0.01 ~ 0.03% However, if the emphasis is on the corrosive side, up to 0.5% by weight is a possible concentration range.

As described above, the azadenine coating layer formed on the steel cord according to the method of the present invention is excellent in improving the corrosion resistance even when using a low concentration of solution, it will have an excellent effect in extending the life of the tire when used as a tire reinforcement material It is expected.

In addition, since the corrosion resistance of the steel cord can be controlled by adjusting the concentration of azadenine, the present invention has an advantage of effectively suppressing surface degradation of a steel cord product that is exposed to the air for a long time.

Claims (5)

A brass plating layer composed of 60 to 70 wt% copper and 30 to 40 wt% zinc is formed on the surface, and a plurality of brass plated filaments obtained by cold drawing high carbon steel wire having a carbon content of 0.6 to 0.85 wt% are twisted together. In the steel cord for tire reinforcement made, The surface of each brass plated filament constituting the steel cord is a steel tire cord with improved corrosion resistance, characterized in that the dried 8- azadenine coating layer is formed. A brass plating layer composed of 60 to 70 wt% copper and 30 to 40 wt% zinc is formed on the surface, and a plurality of brass plated filaments obtained by cold drawing high carbon steel wire having a carbon content of 0.6 to 0.85 wt% are twisted together. In the steel cord for tire reinforcement made, The steel tire cord with improved corrosion resistance, characterized in that the dried 8- azadenine coating layer is formed on the outer peripheral surface of the steel cord. A brass plating layer composed of 60 to 70 wt% copper and 30 to 40 wt% zinc is formed on the surface, and a plurality of brass plated filaments formed by cold drawing high carbon steel wire having a carbon content of 0.6 to 0.85 wt% are combined. In manufacturing the code, Depositing the drawn brass plated filament in an 8-azadenine solution to apply an 8-azadenine solution to the surface of the brass plated layer of the brass plated filament; Drying the 8-azadenine solution coating layer applied to the surface of the brass plated filament with hot air of 200 ° C. or higher; Winding up a brass plated filament having a dried 8-azadenine coating layer formed on a surface thereof; A method of manufacturing a steel tire cord having improved corrosion resistance, characterized in that the dried 8-azadenin coating layer comprises a step of manufacturing a steel cord by associating a plurality of brass plated filaments formed on a surface thereof. A brass plating layer composed of 60 to 70 wt% copper and 30 to 40 wt% zinc is formed on the surface, and a plurality of brass plated filaments formed by cold drawing high carbon steel wire having a carbon content of 0.6 to 0.85 wt% are combined. In manufacturing the code, Manufacturing a steel cord by assembling a plurality of the drawn brass plated filaments; Depositing the steel cord consisting of a plurality of brass plated filaments in an 8-azadenin solution to apply an 8-azadenin solution to the outer circumferential surface of the steel cord; Drying the 8-azadenine solution coating layer applied to the outer circumferential surface of the steel cord with hot air of 200 ° C. or higher; A method for producing a steel tire cord having improved corrosion resistance, characterized in that the dried 8-azadenine coating layer comprises winding a steel cord coated on the outer circumferential surface thereof. The steel having improved corrosion resistance according to claim 3, wherein the 8-azadenine solution is a solution obtained by heating and dissolving 0.01-0.5% by weight of 8-azadenine in one of water, methanol or acetone as a solvent. Method of manufacturing tire cords.